The present invention relates to the operation of dual-mode phones, and more particularly, to extending Private Branch Exchange (PBX) functionality in dual-mode phones.
Dual-mode phones support connections via Wi-Fi and cellular networks. While associated with the enterprise Wi-Fi network, the user places and receives calls through the enterprise Wi-Fi system. While out of range of the enterprise Wi-Fi network, the user places and receives calls through the cellular system.
As viewed from the point of view of the enterprise, dual-mode phones allow the enterprise to maintain connectivity with the user via the cellular network when the user is out of range of enterprise Wi-Fi coverage.
A problem arises however, as the enterprise PBX provides suite of capabilities to local enterprise users, and the cellular system provides different capabilities, most often a subset of those enterprise capabilities, to cellular users. When in the range of the enterprise Wi-Fi system, the dual-mode phone user can interact with the enterprise PBX through Session Initiation Protocol (SIP) Wi-Fi signaling. But when the dual-mode phone is connected to the cellular network, this signaling is not available.
What is needed is a method of extending enterprise PBX capabilities in a dual-mode phone connected through the cellular network.